1. Field of the Invention
The present invention relates generally to a locking system and more particularly to a locking system for storage unit doors.
2. Background Information
The use of walk-in storage units for storing household, office, and other items has increased dramatically in recent years. Unfortunately, there has also been a dramatic increase in theft of items from storage units which results in a need for more effective locking systems for the storage units.
Exterior walls of a typical storage unit are made of corrugated sheet metal. The storage unit doors are typically either horizontally swinging or roll-up type doors also made of corrugated sheet metal. Framing the door entrance is a sheet metal doorjamb.
Traditionally, the storage unit door is closed with a sliding bolt mechanism which can include a lock. The locking mechanism is secured to the door and has a member extending beyond the vertical edge of the door which abuts the doorjamb when the door is closed. The bolt mechanism slides behind the doorjamb to trap the doorjamb between the bolt and the extending member to prevent the door from swinging open. Traditionally, these sliding bolts were locked and held in place by means of a padlock. However, thieves easily overcome these locks by simply cutting the padlocks with bolt cutters when no one is around.
In an attempt to solve this problem, the sliding bolt mechanisms were designed with a recessed lock as shown in FIGS. 1 and 2. The recessed lock inserts through a hole in the door plate and a matching, aligned hole in the bolt when the bolt is slid into a locking position. When the recessed lock is inserted through the holes and turned with a key, it is locked in position and holds the bolt in the locking position. Once again, thieves are able to overcome this locking mechanism by prying the doorjamb with a crowbar or other prying device thereby allowing the bolt and door to swing free. It is desirable to have a slide-bolt locking mechanism with a key activated recess lock for a storage unit door which cannot be overcome by prying the doorjamb with a prying device to free the bolt and open the door.
It is an object of this invention to provide an improved storage unit door locking system to prevent forced entry.
It is a further object of this invention to provide a locking system for a storage unit door which utilizes a recessed locking device.
It is a further object of this invention to provide a locking system for a storage unit door which utilizes a sliding bolt for ease of operation.
It is a further object of this invention to provide a locking system for a storage unit door which prevents forced entry by the use of a prying device to pry the doorjamb to free the locking bolt.
It is a further object of this invention to provide a locking system for a storage unit door which secures the locking bolt to the doorjamb.
In order to achieve these objectives, this invention provides for a locking mechanism which is comprised of a door plate which is affixed to the storage unit door. The door plate is equipped with an extension plate which extends beyond the vertical edge of the storage unit door such that when the door is closed, the extension plate abuts the doorjamb and is flush against the doorjamb. The door plate is further equipped with a sliding bolt behind the door plate which slides behind the doorjamb and traps the doorjamb between the extension plate and sliding bolt.
A recessed lock is used to lock and hold the sliding bolt into place. The recessed lock slides into matching, aligned holes in the extension plate, doorjamb and the sliding bolt. When the recessed lock is inserted into the holes and the key is turned and removed, the recessed lock is locked in place and further locks the sliding bolt and extension plate in place. Since the doorjamb is physically locked to the steel extension plate and steel sliding bolt, it cannot be pried open with the use of a crowbar.